Spatial analysis of the ecological relationships of urban carbon metabolism based on an 18 nodes network model

The study of carbon metabolism from the perspective of a network has received much attention in ecological simulation. The present study focused on the previous analysis of natural metabolism, and we generated a spatial network model with 18 nodes consisting of natural and technical metabolic components. We combined flow and utility analysis using the ecological network method to quantitatively analyze the structure of the ecological relationships and summarize the key metabolic functions among different relationships of Beijing. The positive or negative effect of these relationships on the system was also explored. Furthermore, we used the GIS method to map the different relationships and examine their flux to characterize the spatial variations of Beijing. We concluded that transportation and industrial land, cultivated and urban land were the main components that contributed to exploitation and control relationships, resulting in excessive carbon emissions during urban sprawl. Natural metabolic components and cultivated land were the foundation of mutualism relationships that increase carbon sequestration. Beijing needs more space to develop mutualism relationships while cutting down on the carbon emission brought by the competition relationships. The results will guide the optimization of the spatial structure in urban areas, and the well-constructed framework could be applied to future urban planning.